In Mayor, Etc. of New York v. George Miln., the Supreme Court ruled that a state law could not be used to interfere with or supersede federal laws and treaties. The case involved a dispute between the City of New York and an immigrant from Scotland named George Miln who had been arrested for failing to pay his passage fee upon arriving in the United States. The city argued that it was entitled to collect this fee under a state law, but Miln countered that he had already paid his fare according to an existing treaty between Great Britain and America which exempted British subjects from such fees when entering American ports. In its ruling, the court held that since Congress is responsible for making all laws concerning foreign affairs, any conflicting state legislation must yield in favor of federal authority on this matter; thus affirming both congressional supremacy over states as well as international agreements made by our government with other nations.

In Mayor, Etc. of New York v. George Miln., the Supreme Court was tasked with determining whether a state law that allowed for the seizure and sale of goods to pay off debts violated the Constitution's prohibition against bills of attainder. The majority opinion held that it did not violate this provision because it applied equally to all debtors in similar situations and did not single out any particular individual or group for punishment without trial by jury. However, Justice McLean dissented from this opinion on two grounds: firstly, he argued that since there was no judicial proceeding involved in seizing and selling property under this law, it constituted an act of legislative power which should be reserved only for courts; secondly, he contended that even if such proceedings were permissible under certain circumstances they must still comply with constitutional requirements such as due process protections like notice before action is taken against someone's property rights. In conclusion, Justice McLean believed that while states may have some authority over their citizens' affairs they must always remain mindful of their obligations to uphold fundamental principles enshrined in our nation’s founding documents when exercising those powers.